Wavelength-selective thermal emitters (WS-EMs) hold considerable appeal due to the scarcity of cost-effective, narrow-band sources in the mid-to-long-wave infrared spectrum. WS-EMs achieved via dielectric materials typically exhibit thermal emission peaks with high quality factors (
Thermal emission is the radiation of electromagnetic waves from hot objects. The promise of thermal‐emission engineering for applications in energy harvesting, radiative cooling, and thermal camouflage has recently led to renewed research interest in this topic. However, accurate and precise measurements of thermal emission in a laboratory setting can be challenging in part due to the presence of background emission from the surrounding environment and the measurement instrument itself. This problem is especially acute for thermal emitters that have unconventional temperature dependence, operate at low temperatures, or are out of equilibrium. In this paper, general procedures are described, recommended, and demonstrated for thermal‐emission measurements that can accommodate such unconventional thermal emitters.
more » « less- Award ID(s):
- 1750341
- NSF-PAR ID:
- 10456146
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Laser & Photonics Reviews
- Volume:
- 14
- Issue:
- 8
- ISSN:
- 1863-8880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Q factors), but their optical responses are prone to temperature fluctuations. Metallic EMs, on the other hand, show negligible drifts with temperature changes, but theirQ factors usually hover around 10. In this study, we introduce and experimentally verify an EM grounded in plasmonic quasi-bound states in the continuum (BICs) within a mirror-coupled system. Our design numerically delivers an ultra-narrowband single peak with aQ factor of approximately 64 and near-unity absorptance that can be freely tuned within an expansive band of more than 10 µm. By introducing air slots symmetrically, theQ factor can be further augmented to around 100. Multipolar analysis and phase diagrams are presented to elucidate the operational principle. Importantly, our infrared spectral measurements affirm the remarkable resilience of our designs’ resonance frequency in the face of temperature fluctuations over 300°C. Additionally, we develop an effective impedance model based on the optical nanoantenna theory to understand how further tuning of the emission properties is achieved through precise engineering of the slot. This research thus heralds the potential of applying plasmonic quasi-BICs in designing ultra-narrowband, temperature-stable thermal emitters in the mid-infrared. Moreover, such a concept may be adaptable to other frequency ranges, such as near-infrared, terahertz, and gigahertz. -
more » « less
Abstract All open systems that exchange energy with their environment are non‐Hermitian. Thermal emitters are open systems that can benefit from the rich set of physical phenomena enabled by their non‐Hermitian description. Using phase, symmetry, chirality, and topology, thermal radiation from hot surfaces can be unconventionally engineered to generate light with new states. Such thermal emitters are necessary for a wide variety of applications in sensing and energy conversion. Here, a non‐Hermitian selective thermal emitter is experimentally demonstrated, which exhibits passive
PT ‐symmetry in thermal emission at 700 °C. Furthermore, the effect of internal phase of the oscillator system on far‐field thermal radiation is experimentally demonstrated. The ability to tune the oscillator phase provides new pathways for both engineering and controlling selective thermal emitters for applications in sensing and energy conversion. -
more » « less
Abstract Experimental research shows that isoprene emission by plants can improve photosynthetic performance at high temperatures. But whether species that emit isoprene have higher thermal limits than non‐emitting species remains largely untested. Tropical plants are adapted to narrow temperature ranges and global warming could result in significant ecosystem restructuring due to small variations in species' thermal tolerances. We compared photosynthetic temperature responses of 26 co‐occurring tropical tree and liana species to test whether isoprene‐emitting species are more tolerant to high temperatures. We classified species as isoprene emitters versus non‐emitters based on published datasets. Maximum temperatures for net photosynthesis were ~1.8°C higher for isoprene‐emitting species than for non‐emitters, and thermal response curves were 24% wider; differences in optimum temperatures (Topt) or photosynthetic rates at Toptwere not significant. Modelling the carbon cost of isoprene emission, we show that even strong emission rates cause little reduction in the net carbon assimilation advantage over non‐emitters at supraoptimal temperatures. Isoprene emissions may alleviate biochemical limitations, which together with stomatal conductance, co‐limit photosynthesis above Topt. Our findings provide evidence that isoprene emission may be an adaptation to warmer thermal niches, and that emitting species may fare better under global warming than co‐occurring non‐emitting species.
-
more » « less
Abstract We present a search for extreme emission line galaxies (EELGs) at
z < 1 in the COSMOS and North Ecliptic Pole (NEP) fields with imaging from Subaru/Hyper Suprime-Cam (HSC) and a combination of new and existing spectroscopy. We select EELGs on the basis of substantial excess flux in thez broad band, which is sensitive to Hα at 0.3 ≲z ≲ 0.42 and [Oiii ]λ 5007 at 0.7 ≲z ≲ 0.86. We identify 10,470 galaxies withz excesses in the COSMOS data set and 91,385 in the NEP field. We cross-reference the COSMOS EELG sample with the zCOSMOS and DEIMOS 10k spectral catalogs, finding 1395 spectroscopic matches. We made an additional 71 (46 unique) spectroscopic measurements withY < 23 using the HYDRA multiobject spectrograph on the WIYN 3.5 m telescope, and 204 spectroscopic measurements from the DEIMOS spectrograph on the Keck II telescope, providing a total of 1441/10,470 spectroscopic redshifts for the EELG sample in COSMOS (∼14%). We confirm that 1418 (∼98%) are Hα or [Oiii ]λ 5007 emitters in the above stated redshift ranges. We also identify 240 redshifted Hα and [Oiii ]λ 5007 emitters in the NEP using spectra taken with WIYN/HYDRA and Keck/DEIMOS. Using broadband-selection techniques in theg −r −i color space, we distinguish between Hα and [Oiii ]λ 5007 emitters with 98.6% accuracy. We test our EELG selection by constructing Hα and [Oiii ]λ 5007 luminosity functions and comparing to recent literature results. We conclude that broadband magnitudes from HSC, the Vera C. Rubin Observatory, and other deep optical multiband surveys can be used to select EELGs in a straightforward manner. -
more » « less
Abstract Here, ultra‐long lifetimes of defect‐trapped single quantum emitters (SQEs) in monolayer WSe2/hBN heterostructures are reported. The lifetimes of these SQEs are approximately 225 ns, more than two orders of magnitude larger than what has been previously reported for defect‐trapped excitons in WSe2. These SQEs consist of co‐linearly polarized doublet peaks with a fine structure splitting of 0.45 meV. Second‐order correlation measurements show antibunched single‐photon emission with a g(2)(0) value of ≈0.13. Through numerical analysis and modeling, it is shown how such long‐lifetime single emitters can arise from bright and dark exciton coupling in antisite defects on the W sites. Additionally, high‐quality single‐photon emission over a wide range of lifetimes—from 2 ns to over 200 ns—is also reported, suggesting a variety of other possible defect structures present. The flexibility to generate high fidelity single‐photon emission, over a wide range of lifetimes in a single material system, has potential in many optical quantum computing applications from high‐bit‐rate single‐photon sources to quantum memory devices.
